1. Field of the Invention
The present invention relates to the field of photography and, more particularly, to a processor for processing large format film units of the self-developing type.
2. Description of the Prior Art
Large format (e.g. 8 .times.10 or 10 .times.12) self- developing film units are used in a variety of applications. For example, X-ray-type film units are employed in the industrial and medical fields to provide instant radiographs. Reflection print film units (black and white or color) are used mostly for industrial, advertising and portrait photography.
The film units are generally loaded into a light- tight cassette and are exposed in conventional view cameras or X-ray apparatus.
After exposure, the cassette is moved to a processor which extracts the film from the cassette and, by the application of compressive pressure, distributes a fluid processing composition between predetermined layers of the film unit to initiate a well known diffusion transfer process.
In their most common form, each film unit includes a photosensitive element comprising an opaque or translucent support sheet having one or more photosensitive layers thereon and an image-receiving element comprising an opaque or translucent support sheet having one or more image- receiving layers thereon and a rupturable container of fluid processing composition coupled to the leading end of the support sheet.
The two sheets may be coupled together at their respective leading ends by a leader such that the two elements may be extracted simultaneously from the cassette in super- position with the photosensitive and image-receiving layers in face-to-face relation.
The leader is generally fed between pressure- applying members in the processor, e.g., a pair of juxtaposed rollers, which serve to apply a compressive pressure progressively along the length of the film unit to rupture the container and distribute the fluid between the photo- sensitive and image-receiving layers as the film unit is advanced relative to the "pressure-applying" members.
After a suitable imbibition period, the two sheets may be separated to reveal a positive image on the image- receiving sheet.
In addition to processing the film units, the processor must provide a substantially light-free environment for the imbibition period because not all self-developing film units include a complete self-contained opacification system. For example, the X-ray film units have outer support sheets which are slightly translucent.
This function is usually provided by a film receiving dark chamber. Even if the film unit is self-opacifying (most reflection print types other than X-ray), the dark chamber light seals the light path between and around the rollers to prevent fogging of that part of the film unit between the cassette and the entry side of the rollers.
Considering the large size of the film units, cassetts, and view cameras or portable X-ray apparatus, it is highly desirable that the processor be portable, compact, and easy to carry, store and use.
Examples of previously know compact and portable larger format processing systems (processor, film units, and cassettes) may be found in U.S. Pat. Nos. 3,788,205; 3,802,887; 3,804,625; and 3,854,812. In these systems, compactness is achieved by storing the processed film unit for imbibition in a coiled or curved condition.
For example, in the first three patents, the film unit is warapped onto a cylindrical drum for fluid distribution and imbibition storage.
In the last patent, the film unit emerges from the exit side of a pair of rollers and is advanced into a semicircular dark chamber. Also, the cassette is supported on the outside of the processor housing to further enhance compactness and portability.
Other compact processors employ a linear film unit path of travel into a flat receiving chamber. For example, see U.S. Pat. No. 2,689,306 (FIGS. 13, 16, 17, and 18) wherein the cassette is supported such that a major portion of its length extends outside of the processor housing and the film unit is andvanced into a linear receiving chamber within the processor housing.
The use of auxiliary dark chambers (one that attaches to and extends beyond the main processor housing) for reducing the overall storage size of a processing system is also known in the prior art. See U.S. Pat. No. 2,638,828 wherein the auxiliary dark chamber is pivotally mounted (detachable) on the main processor housing in communication with a film exit slot. This patent suggests (Col. 3, lines 22 to 27) that the auxiliary chamber may be removed and stored within the main processor housing when the processor is not in use.
For other examples of processors with pivoting imbibition chambers, see U.S. Pat. Nos. 3,344,730 and 3,364,835. Examples of self-developing cameras having pivoting, expansible, or detachable imbibition chambers are found in U.S. pat. Nos. 2,451,820; 2,467,320; 3,369,469; and 3,650,188. Note should also be taken of U.S. Pat. No. 3,165,046 which discloses a portable document copier having a multifunction carrying handle thereon. The reason for this will become apparent later on in this disclosure.
Each of the noted prior art compact processors performs the intended film processing function in a satisfactory manner. However in certain applications there may be limitations to the particular construction employed.
For example, in some applications, such as aerial or portrait and advertising photography, one may not wish to use a processor in which the processed film unit is stored in a curved condition for imbibition because of the tendency to induce a slight and temporary curl in the photograph. Therefore one would choose, most likely, a processor having a linear dark chamber for storing the film unit in a flat condition.
If setup and dismantling time are important, one may not wish to choose a processor that has a dark chamber which must be detached from its operative position for storage elsewhere.